var arr =[10,50,84,96,25,0,500,305];

var min=arr[0];

var max=arr[0];

for (var i=0;i<arr.length;i++){
    if (arr[i]>max){
        max=arr[i];
    }
    if (arr[i]<min){
        min=arr[i];
    }
}

console.log("最大值"+max);
console.log("最小值"+min);